Integrated Functions (Continued)
Table 4-44. PCI Configuration Registers (Continued)
Bit
Name
Description
Index 44h
PCI Arbitration Control 2 Register (R/W)
Default Value = 00h
7
PP
Ping-Pong:
0 = Arbiter grants the processor bus per the setting of bits [2:0].
1 = Arbiter grants the processor bus ownership of the PCI bus every other arbitration cycle.
6:4
FAC
Fixed Arbitration Controls: These bits control the priority under fixed arbitration. The priority table is as
follows (priority listed highest to lowest):
000 = REQ0#, REQ1#, REQ2#
001 = REQ1#, REQ0#, REQ2#
010 = REQ0#, REQ2#,REQ1#
011 = Reserved
100 = REQ1#, REQ2#, REQ0#
101 = Reserved
110 = REQ2#, REQ1#, REQ0#
111 = REQ2#, REQ0#, REQ1#
Note: The rotation arbitration bits [2:0] must be set to 000 for full fixed arbitration. If rotation bits are not
set to 000, then hybrid arbitration will occur. If Ping-Pong is enabled (bit 7 = 1), the processor will
have priority every other arbitration. In this mode, the arbiter grants the PCI bus to a master and
ignores all other requests. When the master finishes, the processor will be guaranteed access. At
this point PCI requests will again be recognized. This will switch arbitration from CPU to PCI to
CPU to PCI, etc.
3
RSVD
RAC
Reserved: Set to 0.
2:0
Rotating Arbitration Controls: These bits control the priority under rotating arbitration.
000 = Fixed arbitration will occur.
111 = Full rotating arbitration will occur.
When these bits are set to other values, hybrid arbitration will occur.
Index 45h-FFh
Reserved
Default Value = 00h
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